1. Field of the Invention
The present invention relates to a probe for a hair cell, and a labelling method for a hair cell using the probe for a hair cell.
2. Description of the Related Art
In a human, a hair cell exists in the cochlea which is an auditory receptor, and in the semicircular canals and vestibular organs both of which are vestibular sensory receptors. The hair cell is covered with special cilia. The cilia perceive the movement of lymph generated depending on a sound, a motion, and a posture, and then cause an electrical change.
The abnormality of the hair cell is said to relate to factors of disorders such as peripheral sensorineural auditory impairment (hearing loss), tinnitus, and vertigo. The hair cell itself is active in metabolism, and in particular, is fragile to and easily damaged by the expose to noise and chemicals. A list of medicaments and chemical substances which may have hair cell toxicity has been reported. The list includes, for example, an antibiotic such as an aminoglycoside antibiotic, an anti-inflammatory drug, a diuretic drug, an antimalarial drug, an antitumor drug, and a topical agent (Drug Safety: an International Journal of Medical Toxicology and Drug Experience, 14(3), pp. 198-212, 1996).
However, thus far, there is no standardized screening method for auditory toxicity in a drug development stage, and further, many of already approved medicaments remain unknown for their auditory toxicity.
For means for evaluating the auditory toxicity of a chemical substance, for example, means for evaluating the life and death of a hair cell of Zebrafish with a fluorescent dye such as 2-(4-(dimethylamino)styryl)-N-ethylpyridinium iodide (DASPEI) is reported (Hearing Research, 208, pp. 79-88, 2005). Further, FM1-43 is known as a hair cell staining dyestuff (The Journal of Histochemistry and Cytochemistry, 44(7), pp. 733-741, 1996).
For an expression mechanism of the auditory toxicity with a chemical substance, various modes may be estimated. That is, there is a diversity in the type of injuries on a′ hair cell function due to a difference in a target biomolecule (such as a protein, an enzyme, a nucleic acid, and a gene) of a chemical substance. Accordingly, it is important to identify various conditions of a hair cell (for example, loss of a specific cell function as well as life and death of a cell) depending on the diversity in the type of injuries. Therefore, there is a demand for hair cell staining agents having various chemical structures.
However, known compounds for staining a hair cell are only the two kinds (DASPEI and FM1-43) exemplified above. Those compounds are close to each other in terms of the excitation wavelength and fluorescence emission wavelength, and they do not sufficiently contribute to enlargement of variations for selection of staining technologies depending on the above mentioned diversity in modes and on the purposes such as multiple staining.